• 제목/요약/키워드: fracture tests

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다공성 칼슘포스파이트에 대한 파괴분석 (Numerical analysis of fracture mechanisms for porous calcium phosphate)

  • 박진홍;배지용;심재범;전인수
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2008년도 추계학술대회A
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    • pp.1301-1302
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    • 2008
  • In this study, the fracture strength for fracture mechanism porous calcium phosphate made from sintered with ${\beta}$-tricalcium phosphate obtained by wet precipitation procedure is analyzed using finite element method and experiment measurement. First, three $3{\times}3{\times}3mm^3$ and $5{\times}5{\times}5mm^3$ specimens are prepared and tomographic images of one $5{\times}5{\times}5mm^3$ specimen are obtained by micro focus X-ray CT. The compression tests using the specimens are carried out to measure the elastic modulus and fracture strength to analyze the fracture mechanism of porous calcium phosphate specimen. The tomographic images are reconstructed by 3D reconstruction program. The finite elements are directly built up in the reconstructed specimen. The numerical simulation for the compression tests is performed using the element. The mechanism of calcium phosphate of simulation are obtained by the compression tests using there cylindric specimen of height 19.5 mm and diameter 10 mm. From the results, the applicability of porous calcium phosphate is evaluated to care fracture and vacant bone of a patient as the reinforcement material.

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The discrete element method simulation and experimental study of determining the mode I stress-intensity factor

  • Shemirani, Alireza Bagher;Haeri, Hadi;Sarfarazi, Vahab;Akbarpour, Abbas;Babanouri, Nima
    • Structural Engineering and Mechanics
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    • 제66권3호
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    • pp.379-386
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    • 2018
  • The present study addresses the direct and indirect methods of determining the mode-I fracture toughness of concrete using experimental tests and particle flow code. The direct method used is compaction tensile test and the indirect methods are notched Brazilian disc test, semi-circular bend specimen test, and hollow center cracked disc. The experiments were carried out to determine which indirect method yields the fracture toughness closer to the one obtained by the direct method. In the numerical analysis, the PFC model was first calibrated with respect to the data obtained from the Brazilian laboratory test. The crack paths observed in the simulated tests were in reasonable accordance with experimental results. The discrete element simulations demonstrated that the macro fractures in the models are caused by microscopic tensile breakages on large numbers of bonded particles. The mode-I fracture toughness in the direct tensile test was smaller than the indirect testing results. The fracture toughness obtained from the SCB test was closer to the direct test results. Hence, the semi-circular bend test is recommended as a proper experiment for determination of mode-I fracture toughness of concrete in the absence of direct tests.

Studies on the effect of thermal shock on crack resistance of 20MnMoNi55 steel using compact tension specimens

  • Thamaraiselvi, K.;Vishnuvardhan, S.
    • Nuclear Engineering and Technology
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    • 제53권9호
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    • pp.3112-3121
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    • 2021
  • One of the major factors affecting the life span of a Reactor Pressure Vessel (RPV) is the Pressurised Thermal Shock (PTS). PTS is a thermo-mechanical load on the RPV wall due to steep temperature gradients and structural load created by internal pressure of the fluid within the RPV. Safe operating life of a nuclear power plant is ensured by carrying out fracture analysis of the RPV against thermal shock. Carrying out fracture tests on RPV/large scale components is not always feasible. Hence, studies on laboratory level specimens are necessary to validate and supplement the prototype results. This paper aims to study the fracture behaviour of standard Compact Tension [C(T)] specimens, made of RPV steel 20MnMoNi55, subjected to thermal shock through experimental and numerical investigations. Fracture tests have been carried out on the C(T) specimens subjected to thermal transient load and tensile load to quantify the effect of thermal shock. Crack resistance curves are obtained from the fracture tests as per ASTM E1820 and compared with those obtained numerically using XFEM and a good agreement was found. A quantitative study on the crack tip plastic zone, computed using cohesive segment approach, from the numerical analyses justified the experimental crack initiation toughness.

영광원자력 배관소재의 재료물성치 평가 (II) -안전주입계통- (Evaluation of Material Properties for Yonggwang Nuclear Piping Systems(II) - Safety Injection System-)

  • 김영진;석창성;장윤석
    • 대한기계학회논문집
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    • 제19권6호
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    • pp.1451-1459
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    • 1995
  • The objective of this paper is to evaluate the material properties of SA312 TP316 and SA312 TP304 stainless steels and their associated welds manufactured for safety injection system of Yonggwang 3,4 nuclear generating stations. A total of 62 tensile tests and 46 fracture toughness tests were conducted and the effects of various parameters such as pipe size, crack plane orientation, tests were conducted and the effects of various parameters such as pipe size, crack plane orientation, test temperature, welding on material properties were discussed. Test results show that the effect of test temperature on fracture toughness was significant while the effects of pipe size and crack plane orientation on fracture toughness were negligible. Fracture toughness of the weld metal was in general higher than that of the base metal.

영광 원자력 발전소 원자로 소재의 가동전 재료 물성 특성 (Evaluation of the Preirradiation Baseline Material Characteristics for Yonggwang Nuclear Reactor Pressure Vessel)

  • 김국철;김정태;석진익;권희경;성운학
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 추계학술대회논문집A
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    • pp.153-158
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    • 2000
  • Nuclear reactor pressure vessel should be safety even in the case that hypothetical defects with allowable size are in vessel. Therefore, the materials should have excellent fracture resistance characteristics. The purpose of this study is to analyze the results of preirradiation baseline test of nuclear pressure vessel for Yonggwang Unit 5/6. In experiments, drop weight tests and impact tests are carried out to obtain nil-ductility transition reference temperature, $RT_{NDT}$ and static and dynamic fracture toughness tests are performed to compare with $K_{IR}$ curve in accordance with ASME Sec.III. The test results show that the materials had sufficiently fracture resistance characteristics for 40 years of design life.

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저방사화 철강재 (JLF-1)의 시험편 크기 변화에 따른 파괴저항곡선의 변화 (Variation of the fracture resistance curve with the change of a size in the specimen of reduced activation ferritic steel (JLF-1))

  • 김동현;윤한기;이상필
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 추계학술대회
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    • pp.1240-1245
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    • 2003
  • Reduced activation ferritic steel (JLF-1) is considered as a promising candidate material for blanket or first-wall structure of D-T fusion reactors. The fracture tests of fracture resistance curve (J-R curve) and $J_{IC}$ are desirable to investigate the exact fracture toughness of JLF-1 steel, since it has a high ductility. The fracture toughness of JLF-1 steel is affected by the configuration of test specimen such side groove, specimen thickness or specimen size. In this study, the fracture toughness tests were performed with various size(plane size and thickness) and various side groove of specimens. The test results showed the standard specimen with the side groove of 40 % represented a valid fracture toughness. The fracture resistance curve increased with increasing plane size and decreased with increasing thickness. However, the fracture resistance curve of half size specimen was similar to that of the standard specimen.

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실배관 파괴특성 평가에 관한 연구 (A Study on the Evaluation of the Pipe Fracture Characteristic)

  • 박재실;김영진;석창성
    • 대한기계학회논문집A
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    • 제29권1호
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    • pp.107-114
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    • 2005
  • In order to analyze the elastic-plastic fracture behavior of a structure, the fracture resistance curve of the material should be known first. The standard CT specimen was used to obtain the fracture resistance curves of a piping system. However, it is known that the fracture resistance curve by the standard CT specimen is very conservative to evaluate the integrity of a structure. Also the fracture resistance curve is effected by the specimen geometry and the dimensions because of the constraint effect. The objective of this paper is to be certain the conservativeness of the fracture resistance curve by the standard CT specimen and to provide an additional safety margin. For these, the fracture tests using a real pipe specimen and the standard CT specimen test were performed. A 4-point bending jig was manufactured for the pipe test and the direct current potential drop method was used to measure the crack extension and the length for the pipe test. Also finite element analyses were performed with a CT specimen and a pipe in order to prove the additional safety margin. From the result of tests and analyses of the pipe and the standard CT specimen, it was observed that the fracture analysis with the standard CT specimen is conservative and the additional safety margin was proved.

크기가 다른 원형공시체의 할렬인장 실험을 통한 모르타르와 콘크리트의 파괴인성연구 (Fracture Toughnesses of Mortar and Concrete Through the Splitting Tensile Tests with Various Sizes of Specimens)

  • 김진근;구헌상;임선택
    • 콘크리트학회지
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    • 제2권3호
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    • pp.89-95
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    • 1990
  • 모르타르와 콘크리트의 파괴특성 연구에 있어 할열인장실험 방법의 가능성을 알아보았다. 이를 위하여 할열인장 실험을 통해 초기노치가 주어져 있는 원형 공시체의 크기가 커질 때 모르타르와 콘크리트의 파괴하중의 변화를 구하였다. 이로부터 SEL방법에 의한 수렴정도가 가장 빠른 것으로 나타났으며 SEL방법이 모르타르와 콘크리트의 파괴에너지 및 파괴인성을 구하는 데 매우 효과적인 방법이 될 수 있음을 보였다.

감육배관의 파괴거동 평가 (Fracture Behavior Evalustion of Pipes with Local Wall Thinning)

  • 안석환;남기우;김선진;김현수;김진환;도재윤
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 추계학술대회논문집A
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    • pp.61-66
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    • 2001
  • Fracture behaviors of pipes with local wall thinning is very important for the integrity of nuclear power plant. In pipes of energy plants, sometimes, the local wall thinning may result from severe drosion-corrosion damage. However, effect of local wall thinning on strength and fracture behaviors of piping system were not well studied. In this paper, the monotonic bending tests were performed of full-scale carbon steel pipes with local wall thinning. A monotonic bending load was applied to straight pipe specimens by four-point loading at ambient temperature without internal pressure. From the tests, fracture behaviors and fracture strength of locally thinned pipe were manifested systematically. The observed failure modes were divided into four types; ovalization, ovalization+cracking, local buckling and local buckling+cracking. Also, maximum load was successfully evaluated.

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두께변화에 따른 엔지니어링 플라스틱의 파괴인성과 AE특성 (Fracture toughness and AE Characteristics of Engineering plastic according to thickness)

  • 남기우;김선진;안병현
    • 한국해양공학회지
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    • 제10권4호
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    • pp.51-57
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    • 1996
  • A standard method for the evalution of the fracture toughness of the high polymer materials has not been fully developed in comparison with that for metallic materials, and has not yet established. In this paper, fracture toughness tests using polycarbonate specimens were carried out. The fracture thughness tests using polycabonate specimens were carried out. The fracture toughness of commercial polycarbonate were dependent on the specimen thickness. The specimen thickness is necessary above 8mm to obtain the valid $K_{IC}$. A cumulative counts were slightly dependent on specimen thickness.

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